I have preperead two amaizing avatar collapsing demo samples with approach that doesn’t use a custom CoordinatorLayoutBehavior!
To view my samples native code: “Collapsing Avatar Toolbar Sample”
To read my “Animation Collapsing Toolbar Android” post on Medium.
demo 1
demo 2 
Instead of use use a custom CoordinatorLayoutBehavior i use an OnOffsetChangedListener which comes from AppBarLayout.
private lateinit var appBarLayout: AppBarLayout
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_demo_1)
...
appBarLayout = findViewById(R.id.app_bar_layout)
/**/
appBarLayout.addOnOffsetChangedListener(
AppBarLayout.OnOffsetChangedListener { appBarLayout, i ->
...
/**/
updateViews(Math.abs(i / appBarLayout.totalScrollRange.toFloat()))
})
}
Demo 1
in updateViews method avatar changes the size and changes avatar’s X, Y position translation in first demo.
private fun updateViews(offset: Float) {
...
/* Collapse avatar img*/
ivUserAvatar.apply {
when {
offset > avatarAnimateStartPointY -> {
val avatarCollapseAnimateOffset = (offset - avatarAnimateStartPointY) * avatarCollapseAnimationChangeWeight
val avatarSize = EXPAND_AVATAR_SIZE - (EXPAND_AVATAR_SIZE - COLLAPSE_IMAGE_SIZE) * avatarCollapseAnimateOffset
this.layoutParams.also {
it.height = Math.round(avatarSize)
it.width = Math.round(avatarSize)
}
invisibleTextViewWorkAround.setTextSize(TypedValue.COMPLEX_UNIT_PX, offset)
this.translationX = ((appBarLayout.width - horizontalToolbarAvatarMargin - avatarSize) / 2) * avatarCollapseAnimateOffset
this.translationY = ((toolbar.height - verticalToolbarAvatarMargin - avatarSize ) / 2) * avatarCollapseAnimateOffset
}
else -> this.layoutParams.also {
if (it.height != EXPAND_AVATAR_SIZE.toInt()) {
it.height = EXPAND_AVATAR_SIZE.toInt()
it.width = EXPAND_AVATAR_SIZE.toInt()
this.layoutParams = it
}
translationX = 0f
}
}
}
}
to find avatarAnimateStartPointY and avatarCollapseAnimationChangeWeight (for convert general offset to avatar animate offset):
private var avatarAnimateStartPointY: Float = 0F
private var avatarCollapseAnimationChangeWeight: Float = 0F
private var isCalculated = false
private var verticalToolbarAvatarMargin =0F
...
if (isCalculated.not()) {
avatarAnimateStartPointY =
Math.abs((appBarLayout.height - (EXPAND_AVATAR_SIZE + horizontalToolbarAvatarMargin)) / appBarLayout.totalScrollRange)
avatarCollapseAnimationChangeWeight = 1 / (1 - avatarAnimateStartPointY)
verticalToolbarAvatarMargin = (toolbar.height - COLLAPSE_IMAGE_SIZE) * 2
isCalculated = true
}
Demo 2
avatar change his size and than animate move to right at one moment with top toolbar text became to show and moving to left.
You need to track states: TO_EXPANDED_STATE changing, TO_COLLAPSED_STATE changing, WAIT_FOR_SWITCH.
/*Collapsed/expended sizes for views*/
val result: Pair<Int, Int> = when {
percentOffset < ABROAD -> {
Pair(TO_EXPANDED_STATE, cashCollapseState?.second ?: WAIT_FOR_SWITCH)
}
else -> {
Pair(TO_COLLAPSED_STATE, cashCollapseState?.second ?: WAIT_FOR_SWITCH)
}
}
Create animation for avatar on state switch change:
result.apply {
var translationY = 0f
var headContainerHeight = 0f
val translationX: Float
var currentImageSize = 0
when {
cashCollapseState != null && cashCollapseState != this -> {
when (first) {
TO_EXPANDED_STATE -> {
translationY = toolbar.height.toFloat()
headContainerHeight = appBarLayout.totalScrollRange.toFloat()
currentImageSize = EXPAND_AVATAR_SIZE.toInt()
/**/
titleToolbarText.visibility = View.VISIBLE
titleToolbarTextSingle.visibility = View.INVISIBLE
background.setBackgroundColor(ContextCompat.getColor(this@Demo2Activity, R.color.color_transparent))
/**/
ivAvatar.translationX = 0f
}
TO_COLLAPSED_STATE -> {
background.setBackgroundColor(ContextCompat.getColor(this@Demo2Activity, R.color.colorPrimary))
currentImageSize = COLLAPSE_IMAGE_SIZE.toInt()
translationY = appBarLayout.totalScrollRange.toFloat() - (toolbar.height - COLLAPSE_IMAGE_SIZE) / 2
headContainerHeight = toolbar.height.toFloat()
translationX = appBarLayout.width / 2f - COLLAPSE_IMAGE_SIZE / 2 - margin * 2
/**/
ValueAnimator.ofFloat(ivAvatar.translationX, translationX).apply {
addUpdateListener {
if (cashCollapseState!!.first == TO_COLLAPSED_STATE) {
ivAvatar.translationX = it.animatedValue as Float
}
}
interpolator = AnticipateOvershootInterpolator()
startDelay = 69
duration = 350
start()
}
...
}
}
ivAvatar.apply {
layoutParams.height = currentImageSize
layoutParams.width = currentImageSize
}
collapsingAvatarContainer.apply {
layoutParams.height = headContainerHeight.toInt()
this.translationY = translationY
requestLayout()
}
/**/
cashCollapseState = Pair(first, SWITCHED)
}
To view my samples native code: “Collapsing Avatar Toolbar Sample”